Under-plank for watertight balcony sub-floor system

Abstract

The present invention relates to a watertight sub-floor system for balcony or roof, in the form of a semi-rigid rollable plank of corrugated polymeric type installed in juxtaposition to form a waterproof flooring between boards and beams. Under-plank are unwrapped and cut at a desired length to avoid transverse junction with respect to water flow. Under-planks overlap parallel to water flow without loss of sealing. The corrugated under-plank has a design of crests and dips, crests widened and sloping to make possible the receiving of screws from deck board, thereby permitting the descent of water trickling from around the damaging screwing of the under-plank, and dips which bear no perforations from screwing and merely allow water to run off to protect wood structures of patios, balconies or terraces against moisture causing premature rot and to protect objects (bike, mowers . . . ) under a deck.

1. A combination of a corrugated under-plank used between a board and a structure element and comprising:
 a rigid film having at least three crests and two dips to provide support over said structural element, at least two sloping sections, 
 a spacing to receive screws between said crests and said dips, said sloping sections providing means of drainage when a liquid is found around said screws, 
 said rigid film comprising a connection zone having a flat dip terminated on a terminating edge which matches a forward edge of a second under-plank in order to allow a variation of spacing between one under-plank and the next one, said variation being equal to the variation of spacing between two boards, 
 said connection zone making possible adjusting boards for the covering of a patio laid out above said connection zone. 
 
     
     
       2. The under-plank of  claim 1  wherein said connection zone is located below said board to avoid receiving matter directly from a spacing between a board and a neighbouring one. 
     
     
       3. The under-plank of  claim 1  wherein said crests are positioned under a board in areas for supporting said board while initiating a slope, defining accentuated left crests, central, right and left crests and a flat bottom, said spacing to receive said screws corresponding to spaces on both sides of left and right crests indicated according as a zone available for screwing comprising a widened zone of screwing and an abrupt zone of screwing being narrower than said widened zone of screwing. 
     
     
       4. The under-plank of  claim 3  wherein said widened zones of screwing and said abrupt zones of screwing have a slope of at least 2 degrees which permit water to run out instead of remaining imprisoned between boards of an under-plank. 
     
     
       5. The under-plank of  claim 3  being part of a number of under-planks installed on beams to support said right and left crests while being moulded according to the shape of said crests. 
     
     
       6. The under-plank of  claim 5  wherein said number of under-planks are continuous.